Hitherto, ceramic porous materials have been used in extensive applications such as various filters (for gas separation, solid separation, sterilization, dust removal, etc.), drying agents, adsorbents, purifying agents, deodorants, carriers for catalysts, sound absorbing materials, heat insulating materials and sensors, or the like, because they are excellent in heat resistance, impact resistance, chemical resistance and strength characteristics at an ordinary temperature and a high temperature, and have a reduced weight. Thus, the ceramic porous materials have now become an indispensable industrial material.
The ceramic porous materials used in the above applications are required to satisfy various properties such as pore distribution and pore volume. For example, the ceramic porous materials used as a carrier for catalysts are required to have a large pore volume so as to support a large amount of a catalyst component thereon. In addition, when used a carrier for catalysts or an adsorbent in a fixed bed facility, the ceramic porous materials are required to have a high strength so as not to suffer from collapse upon removal or filling of the catalysts. Therefore, there is a demand for the ceramic molding product capable of exhibiting both of the properties, i.e., a large pore volume and a high strength.
However, in recent years, in the application fields such as the filters and the carriers for catalysts, the ceramic porous materials have been required to exhibit a larger specific surface area, a higher strength and a more excellent heat resistance. Therefore, it may become difficult for the conventional ceramic porous materials to satisfy all of these requirements. Porous alumina used as various filters or carriers for catalysts mainly comprises γ-alumina. However, the γ-alumina tends to undergo phase transfer into α-alumina as a stabilized phase when exposed to a high temperature near 1000° C., thereby causing the problems such as considerable reduction in specific surface area and therefore lack of its function as a carrier for catalysts.
General alumina-based molded products and magnesia molded products have been conventionally reported (Patent Documents 1 to 4).
Patent Document 1: Japanese Patent Application Laid-Open (KOKAI) No. 2003-48768
Patent Document 2: Japanese Patent Application Laid-Open (KOKAI) No. 2007-117916
Patent Document 3 Japanese Patent Application Laid-Open (KOKAI) No. 2004-168629
Patent Document 4: Japanese Patent Application Laid-Open (KOKAI) No. 2003-284949